1. Field of the Invention
The invention relates to a vacuum device, and more particularly to the vacuum device that the airflow thereof at a flow outlet can be detected.
2. Description of the Prior Art
To the vacuum device in the art, a fan, a filter member and a dust-collecting box are generally built inside the device body, in which the fan is to provide an airflow for sucking foreign dusts, particles and small-size garbage into the dust-collecting box of the vacuum device via the filter member. Also, the clean airflow posterior to the filter member after leaving the dusts, the particles and the garbage inside the device body is then exhausted to the atmosphere.
However, since the dust-collecting box is conventionally mounted inside the device body of the vacuum device, thus, to a user, the instant amount of the dusts, the particles and the garbage collected inside dust-collecting box cannot be observed simply by naked eyes. Therefore, the user usually needs to disassemble the vacuum device frequently for checking the volume collected inside the dust-collecting box, such that the vacuum device can ensure its vacuum performance. Obviously, the aforesaid management upon the conventional vacuum device is somehow cumbersome to the ordinary user. In addition, in some cases, the busy user is quite possible to forget the investigation upon the volume collected inside the dust-collecting box, and thus ill vacuum performance or serious jam at the sucking inlet may occur because of failing to empty the dust-collecting box in time. Under this circumstance, the dust-collecting box may be run without significant efficiency, and thus ill vacuum performance and the waste in energy to the vacuum device are definitely inevitable.